Switching between 3D video and 2D video

ABSTRACT

A three dimensional [3D] video signal is processed in a video device (50). The device has generating means (52) for generating an output signal for transferring the video data via a high-speed digital interface like HDMI to a 3D display, which selectively generate a 3D display signal for displaying the 3D video data on a 3D display operative in a 3D mode, a 2D display signal for displaying 2D video data on the 3D display operative in a 2D mode, or a pseudo 2D display signal by including 2D video data in the output signal for displaying the 2D video data on the 3D display operative in the 3D mode. Processing means (53) detect a request to display 2D video data on the 3D display, while the 3D display is operative in the 3D mode, and, in response to the detection, the generating means are set to generate the pseudo 2D display signal for maintaining the 3D mode of the 3D display.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/524,267 filed Jul. 29, 2019 which is a continuation of U.S. patentapplication Ser. No. 15/898,749 filed Feb. 19, 2018 which is acontinuation of U.S. patent application Ser. No. 13/386,687 filed onJan. 24, 2012 which is a National Stage application of InternationalApplication No. PCT/IB2010/53318 filed Jul. 21, 2010 which claims thebenefit of EP Patent Application 09166461.5 filed on Jul. 27, 2009.These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a video device for processing a threedimensional [3D] video signal, the device comprising receiving means forreceiving the 3D video signal and retrieving 3D video data, andgenerating means for generating an output signal for transferring thevideo data via a high-speed digital interface to a 3D display, thegenerating means being arranged for generating in a 3D mode, as theoutput signal, a 3D display signal for displaying the 3D video data onthe 3D display operative in a 3D mode, and generating in a 2D mode, asthe output signal, a 2D display signal for displaying 2D video data onthe 3D display operative in a 2D mode.

The invention further relates to a method of processing a 3D videosignal, a method of providing a 3D video signal, a signal, a recordcarrier and a computer program product.

The invention relates to the field of selectively rendering 3D videodata and 2D video data on a 3D display device.

BACKGROUND OF THE INVENTION

Devices for generating two dimensional (2D) video data are known, forexample video servers, broadcasters, or authoring devices. Currently 3Denhanced devices for providing three dimensional (3D) image data arebeing proposed. Similarly video devices for processing display 3D videodata are being proposed, like players for optical disc (e.g. Blu-rayDisc; BD) or set top boxes which render received digital video signals.The 3D video device is to be coupled to a 3D display device like a TVset or monitor. Video data is transferred from the source device via asuitable interface, preferably a high-speed digital interface like HDMI.

In addition to 3D content, such as 3D movies or TV broadcasts,additional, auxiliary 2D video data may be displayed, for example amenu, news flash or other announcements. Furthermore, in practice a usermay select 3D video material or 2D video material at will from varioussources. Moreover, the user may apply a setting to force displaying in a2D mode, even when 3D video material is available.

Document WO2009/077929 describes approaches that could be taken totransition between 2D and 3D. A 3D video signal has video informationand associated playback information, the video information andassociated playback information being organized according to a playbackformat. The video information comprises a primary video stream for 2Ddisplay, and an additional information stream for enabling 3D display.The associated playback information comprises display informationindicating the types of display possible. The display information isprocessed at the receiver to determine that both 2D display and 3Ddisplay are possible. A playback mode is set determining whether thevideo information should be displayed in 2D or 3D mode.

SUMMARY OF THE INVENTION

A problem of WO2009/077929 is that transitions between 3D and 2Dplayback that may occur require the display device to change videoformat and frequency. For example, in 3D mode a stereoscopic displayalternates the left and right video in time, to allow a correctsynchronization of the L and R video frames on a HDMI interface with thetiming in the display. The synchronization requires signaling on the H-and/or V sync to correspond with the start of a left and/or right frame.This signaling on the HDMI interface causes the display to re-adjustitself when going from 3D to 2D and vice versa. These re-adjustmentstake time and can be very disturbing to the viewer.

It is an object of the invention to provide a system for transitioningbetween 3D and 2D in a more convenient way.

For this purpose, according to a first aspect of the invention, in thedevice as described in the opening paragraph, the generating means arearranged for generating in a pseudo 2D mode, as the output signal, apseudo 2D display signal by including 2D video data in the output signalin the format of a 3D signal for displaying the 2D video data on the 3Ddisplay operative in the 3D mode, and the device comprises processingmeans for detecting a request for transitioning from the 3D mode todisplay 2D video data on the 3D display, and, in response to thedetection, setting the generating means to generate the pseudo 2Ddisplay signal for maintaining the 3D mode of the 3D display.

For this purpose, according to a further aspect of the invention, themethod of processing 3D video signal comprises

receiving the 3D video signal and retrieving 3D video data;

generating an output signal for transferring the video data via ahigh-speed digital interface to a 3D display, the generating beingarranged for

generating in a 3D mode, as the output signal, a 3D display signal fordisplaying the 3D video data on the 3D display operative in a 3D mode,

generating in a 2D mode, as the output signal, a 2D display signal fordisplaying 2D video data on the 3D display operative in a 2D mode, and

generating in a pseudo 2D mode, as the output signal, a pseudo 2Ddisplay signal by including 2D video data in the output signal in theformat of a 3D signal for displaying the 2D video data on the 3D displayoperative in the 3D mode; and

detecting a request for transitioning from the 3D mode to display 2Dvideo data on the 3D display, and, in response to the detection,

setting the generating means to generate the pseudo 2D display signalfor maintaining the 3D mode of the 3D display.

For this purpose, according to a further aspect of the invention, themethod of providing a 3D video signal for transferring to a 3D videodevice as defined above comprises

generating the 3D video signal comprising 3D video data, and

including a switching indicator in the 3D video signal, the switchingindicator being indicative of a 2D mode to be selected for, in thedevice, when detecting said request to display 2D video data, settingthe generating means to generate the output signal in dependence of theswitching indicator to either the 2D mode or the pseudo 2D mode.

For this purpose, according to a further aspect of the invention, the 3Dvideo signal for transferring 3D video data to a 3D video device asdefined above comprises the 3D video data and a switching indicator, theswitching indicator being indicative of a 2D mode to be selected for, inthe device, while detecting said request to display 2D video data,setting the generating means to generate the output signal in dependenceof the switching indicator to either the 2D mode or the pseudo 2D mode.

The measures have the following effect. When a transition from the 3Dmode to displaying 2D video is initiated, it is determined whether theoutput signal is currently in the 3D mode. If so, the display will alsobe operating in the 3D mode, which display mode is maintained bygenerating the pseudo 2D display signal, i.e. an output signal in theformat of a 3D signal but containing only 2D video information. Thedisplay device continues to receive the display signal in the format ofa 3D signal, and therefore will not switch back to 2D mode orre-synchronize. Advantageously the actual information shown to the userappears to be 2D, because any 3D information is lacking. For example, ina stereo video signal, i.e. 3D based on a left and right view, bothviews will have the same content. Therefore displaying such viewsappears to be 2D to the viewer.

The invention is also based on the following recognition. As consumersget used to viewing in 3D there will be a need to transition between 2Dand 3D and between 3D and 2D. The user will of course expect that thepresentation changes, however this transition should be un-obtrusive,and not cause black frames or other artifacts in the video, which wouldinterfere with the movie experience. When transitioning from 3D to 2Dserious delays and artifacts may occur related to re-configuration ofthe player, the interface signaling and the display. Hence prior to theinvention it was virtually impossible to switch smoothly from 3D to 2Dand back during playback of a movie. To overcome these issues it isproposed that if the user or the system initiates a switch between 3Dand 2D mode, e.g. during 3D mode playback of a movie, that the mode ofthe display is not changed but is forcibly maintained. Thereto theproposed pseudo 2D signal includes 2D video data in the 3D video signalformat. As a result, the presentation of the movie does smoothly changefrom 3D to 2D and vice versa, while the display maintains operative in3D mode. For example this is achieved by a player device, whichgenerates the display signal, by recognizing the situation and reactingdifferently to mode switches during 3D playback than when playback isstopped.

In an embodiment the generating means are arranged for, whentransitioning between the 3D mode and the pseudo 2D mode, to apply a 3Doffset to the 2D video data for changing the amount of 3D information.The effect is that the 2D data achieves a 3D effect in dependence of theoffset. Advantageously applying an offset, e.g. a predetermineddisparity or depth, does not require much calculating power.

In an embodiment the processing means are arranged for, in the pseudo 2Dmode, combining graphical data and video data by positioning thegraphical data in depth direction in front of the 2D video data byapplying an offset to the graphical data to generate a left view and aright view. Advantageously the graphical data is now in front of 2Dvideo data and will not interfere with the video data.

In an embodiment the receiving means are arranged for retrieving, fromthe 3D video signal, a switching indicator, the switching indicatorbeing indicative of a 2D mode to be selected, and the processing meansare arranged for, when detecting said request to display 2D video data,setting the generating means to generate the display signal independence of the switching indicator to either the 2D mode or thepseudo 2D mode. In particular, the 3D video signal including theswitching indicator may be retrieved from a record carrier. The effectis that the originator of the 3D video signal has the opportunity toselect the respective 2D mode that is activated when the user requires2D viewing. Advantageously the originator either may block or allow thepseudo 2D display mode.

Further preferred embodiments of the method, 3D devices and signalaccording to the invention are given in the appended claims, disclosureof which is incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from andelucidated further with reference to the embodiments described by way ofexample in the following description and with reference to theaccompanying drawings, in which

FIG. 1 shows a system for displaying 3D image data,

FIG. 2A shows part of a decoder model of a 3D player,

FIG. 2B shows part of a decoder model of a 3D player,

FIG. 3 shows controlling the pseudo 2D mode,

FIG. 4 shows controlling 3D playback when in the pseudo 2D mode,

FIG. 5A shows a 3D display signal,

FIG. 5B shows a display signal for normal 2D playback,

FIG. 5C shows a display signal for pseudo 2D playback,

FIG. 6A shows applying a 3D offset,

FIG. 6B shows applying a dual 3D offset,

FIG. 6C shows avoiding border cut-off while applying offset,

FIG. 7A shows a stream number table,

FIG. 7B shows a stream number table,

FIG. 8 shows a stream entry,

FIG. 9 shows a table for defining the type in the stream entry, and

FIG. 10 shows the syntax of stream attributes.

In the Figures, elements which correspond to elements already describedhave the same reference numerals.

DETAILED DESCRIPTION OF EMBODIMENTS

It is noted that the current invention may be used for any type of 3Ddisplay that has a depth range. Video data for the 3D displays isassumed to be available as electronic, usually digital, data. Thecurrent invention relates to such image data and manipulates the imagedata in the digital domain.

There are many different ways in which 3D images may be formatted andtransferred, called a 3D video format. Some formats are based on using a2D channel to also carry the stereo information. For example the leftand right view can be interlaced or can be placed side by side and aboveand under. These methods sacrifice resolution to carry the stereoinformation.

A different 3D format is based on two views using a 2D image and anadditional depth image, a so called depth map, which conveys informationabout the depth of objects in the 2D image. The format calledimage+depth is different in that it is a combination of a 2D image witha so called “depth”, or disparity map. This is a gray scale image,whereby the gray scale value of a pixel indicates the amount ofdisparity (or depth in case of a depth map) for the corresponding pixelin the associated 2D image. The display device uses the disparity, depthor parallax map to calculate the additional views taking the 2D image asinput. This may be done in a variety of ways, in the simplest form it isa matter of shifting pixels to the left or right dependent on thedisparity value associated to those pixels. The paper entitled “Depthimage based rendering, compression and transmission for a new approachon 3D TV” by Christoph Fehn gives an excellent overview of thetechnology (see http://iphome.hhi.de/fehn/Publications/fehn_EI2004.pdf).

FIG. 1 shows a system for displaying three dimensional (3D) image data,such as video, graphics or other visual information. A 3D source device40 transfers a 3D video signal 41 to a video device 50. The 3D videosignal may be provided by a remote media server, a broadcaster, etcbased on 3D video data available from storage, from 3D camera's, etc.The video device is coupled to a 3D display device 60 for transferring a3D display signal 56. The 3D video device has an input unit 51 forreceiving the 3D video signal. For example the device may include anoptical disc unit 58 coupled to the input unit for retrieving the 3Dvideo information from an optical record carrier 54 like a DVD orBlu-ray disc. Alternatively, the device may include a network interfaceunit 59 for coupling to a network 45, for example the internet or abroadcast network, such video device usually being called a set-top box.The video device may also be a satellite receiver, a media player, apersonal computer, a mobile device, etc.

In an embodiment the 3D source device has a processing unit 42 fordetermining a switching indicator for switching between a 2D and 3D, andincluding the switching indicator in the 3D video signal, as explainedbelow.

The 3D source device may be a server, a broadcaster, a recording device,or an authoring and/or production system for manufacturing recordcarriers like the Blu-ray Disc. Blu-ray Disc supports an interactiveplatform for content creators. For 3D stereoscopic video there are manyformats. The major formats are stereo and the image-plus-depth format.Of these again there are many possible ways in which the content can beformatted to be suitable for use with new and existing 3D displays anddistribution formats. More information on the Blu-ray Disc format isavailable from the website of the Blu-ray Disc association in a paper onthe audio-visual application format.http://www.blu-raydisc.com/Assets/Downloadablefile/2b_bdrom_audiovisualapplication_0305-12955-15269.pdf. The production process further comprises the steps ofderiving the physical pattern of marks in the tracks which embodies the3D video signal including the depth metadata, and subsequently shapingthe material of the record carrier to provide the tracks of marks on atleast one storage layer.

The 3D video device has a generating unit 52 coupled to the input unit51 for processing the 3D information for generating a 3D display signal56 to be transferred via an output interface unit 55 to the displaydevice, e.g. a display signal according to the HDMI standard, see “HighDefinition Multimedia Interface; Specification Version 1.3a of Nov. 10,2006” available at http://hdmi.org/manufacturer/specification.aspx. Thegenerating unit 52 is arranged for generating the image data included inthe 3D display signal 56 for display on the display device 60.

The generating unit is arranged for generating the display signal 56, ina selected one of the following ways. First the generating means may beset to generate, as the display signal, a 3D display signal fordisplaying the 3D video data on the 3D display operative in a 3D mode.The first status is the traditional generation of a 3D display signal.Secondly, the generating means may be set to generate, as the displaysignal, a 2D display signal for displaying 2D video data on the 3Ddisplay operative in a 2D mode. The second status is the traditional wayof generation of a 2D display signal. The display will be forced tooperate in a 2D display mode. Thirdly, the generating means may be setto generate, as the display signal, a pseudo 2D display signal byincluding 2D video data in the display signal for displaying the 2Dvideo data on the 3D display operative in the 3D mode. It is noted thatthe pseudo 2D signal has the format of a 3D video signal and will behandled by the display as 3D information. However, as the actual videodata embedded in the signal is 2D data, the viewer will experience thevideo in 2D.

The video device has a processing unit 53 for detecting a request todisplay 2D video data on the 3D display. The request includes anycondition that indicates that 2D mode is needed, such as a user commandto switch to 2D mode, the source material may change to 2D sourcematerial, the system may initiate a 2D mode for displaying announcementsor menu's, etc. Secondly, the processing unit detects that the currentoperational mode of the display is 3D, for example by detecting thatcurrently a 3D program is being rendered. Hence it is detected that the3D display is operative in the 3D mode. Finally, in response to thedetection of the request while the display is in 3D mode, the processingunit is arranged for setting the generating means 52 to generate thepseudo 2D display signal for maintaining the 3D mode of the 3D display.

The 3D display device 60 is for displaying 3D image data. The device hasan input interface unit 61 for receiving the 3D display signal 56including the 3D video data transferred from the video device 50. Thetransferred 3D video data is processed in processing unit 62 fordisplaying on a 3D display 63, for example a dual or lenticular LCD. Thedisplay device 60 may be any type of stereoscopic display, also called3D display, and has a display depth range indicated by arrow 64.

Alternatively the processing of the 3D video signal and thetransitioning between 3D and 2D mode is performed in an embodiment ofthe display device. The 3D video data, and optional the switchingindicator, are transferred via the display signal 56. The switching isinitiated locally in the display device, e.g. by a user command. Theprocessing unit 62 now performs the functions of generating the pseudo2D display signals which are directly coupled to the 3D display. Theprocessing means 62 may be arranged for the corresponding functions asdescribed below for the generating means 52 and the processing means 53in the video device.

In a further embodiment the video device 50 and the display device 60are integrated in a single device, where a single set of processingmeans performs said 2D/3D switching functions.

FIG. 1 further shows the record carrier 54 as a carrier of the 3D videosignal. The record carrier is disc-shaped and has a track and a centralhole. The track, constituted by a series of physically detectable marks,is arranged in accordance with a spiral or concentric pattern of turnsconstituting substantially parallel tracks on an information layer. Therecord carrier may be optically readable, called an optical disc, e.g. aCD, DVD or BD (Blu-ray Disc). The information is represented on theinformation layer by the optically detectable marks along the track,e.g. pits and lands. The track structure also comprises positioninformation, e.g. headers and addresses, for indication the location ofunits of information, usually called information blocks. The recordcarrier 54 carries information representing digitally encoded image datalike video, for example encoded according to the MPEG2 or MPEG4 encodingsystem, in a predefined recording format like the DVD or BD format.

In various embodiments the generating means 52 and the processing means53 in the video device are arranged for executing the followingfunctions as described in detail below.

FIGS. 2A and 2B show a decoder model of a 3D player. The player isadapted for playback of stereoscopic 3D content, e.g. a modified Blu-rayDisc player. A disc drive unit 201 is coupled to a disc processor 202for demodulation and error correction (ECC) decoding. Video data isretrieved from the stream read from the disc and a switch 203 provides amain transport stream TS 204 to a buffer 206 coupled to a sourcede-packetizer 208, which provides the data to a PID filter 212, which isa de-multiplexer that identifies the packet identification (PID) fromthe main TS and transfers each type of data to respective buffers 214called EB1-1, EB2-1 for the main 3D video data; EB1-2 and EB2-2 forpresentation graphics data and EB1-3 and EB2-3 for interactive graphicsdata.

Similarly the switch 203 provides a sub transport stream TS 205 to abuffer 207 coupled to a source de-packetizer 209, which provides thedata to a second PID filter 213, which is a de-multiplexer thatidentifies the packet identification (PID) from the sub TS and transferseach type of data also to respective buffers 214.

The de-packetizers 208, 209 also provide initial values 232, 234 toarrival time clock counters 210, 211, which return arrival time clock(i) values 231, 233 to the de-packetizers based on a reference clockgenerator 223.

Respective switches S1-1, S2-2 and S1-3 forward the data to decoder 216(D1) for main 3D video; to decoder 217 (D2) for presentation graphicsand decoder 218 (D3) for interactive graphics. Decoded data istransferred to respective buffers. Main video data is selected by switchS2 from the decoder 216 or the buffer 241, and is transferred to switchS3-1, which provides the final data for a main video Left view 225 and amain video Right view 226.

Similarly Presentation graphics (PG) data from decoder 217 istransferred to respective buffers and a presentation graphics planegenerator 219 cooperating with a color lookup table (CLUT) 221. PG datais selected by switch S3-2 from the generator 219 to provide the finaldata for a PG-Left view 227 and a PG-Right view 228.

Similarly Interactive graphics (IG) data from decoder 218 is transferredto respective buffers and a IG plane generator 220 cooperating with acolor lookup table (CLUT) 222. IG data is selected by switch S3-3 fromthe generator 220 to provide the final data for a IG-Left view 229 and aIG-Right view 230. Interactive user input may be accommodated via input240.

Processing unit 224 controls the operation of the various switches forgenerating the display signal by including in the output either full 3Ddata, normal 2D data or pseudo 2D data.

The function of the device shown in FIG. 2A and FIG. 2B is now furtherdescribed. Packets are filtered from the transport stream that has beretrieved from the disc based on their PID values and stored in thecorresponding buffers indicated by EB1-1 to EB3-3. Packets belonging toelementary streams carrying the main 2D video and the corresponding 2Dgraphics streams are placed in the top buffers EB1-1 through EB1-3 andthe packets for the auxiliary streams for 3D are placed in EB2-1 throughEB2-3. The auxiliary stream may be a dependent stream for encoding rightview data in dependence of left view data of the main stream, or depthdata such as a depth map and transparency data, etc. Switch S1-1 throughto S1-3 selects the appropriate buffers and feeds the packets through tothe decoders D1 to D3. After decoding the decoded video and graphics iscomposited onto the output and selection of the left and right video andgraphics is done by switch S3-1 through to S3-3.

FIG. 3 shows controlling the pseudo 2D mode. The function may beimplemented in a dedicated control unit, or by appropriate controlsoftware in a processor. First at Init 2D 301, it is detected that a 2Ddisplay mode is requested, e.g. by a user command or a system call. Atstep 302 “Detect 2D” the requested 2D display mode is registered, e.g.in a status register. Subsequently either the normal 2D display signalis generated, or the pseudo 2D signal, as follows. At the test “3DMode?” 303 it is determined if the display signal is currently providing3D video data to the 3D display. If Yes, the pseudo 2D signal isgenerated at Pseudo 2D 304. Thereto in step 307, 2D playback in 3D modeis activated by setting (in fact maintaining) Switch S1-1 . . . S1-3 tothe L position, while maintaining the output mode 3D to maintainplayback in 3D mode at the display. However, if No (i.e. the currentplayback is stopped; no 3D material is being rendered), the processcontinues at “Stopped” 305, where the output mode is set to 2D. When itis detected at step 306 “Start 2D” 206 that playback is activated, theplayback is performed by generating a 2D display signal.

It is noted that, by setting the switches to use the left view twice,the generating means are arranged for generating the pseudo 2D displaysignal by deriving image data without 3D information from the input 3Dvideo data. Alternatively, for a image+depth video signal, the depth mapmay be replaced by a single value representing a single depth,preferably at the display surface (zero depth).

It is noted that, when after playback in pseudo 2D mode for a period oftime the user stops the playback, the mode may automatically switch tonormal 2D mode. Alternatively, the display system may remain in pseudo2D until the user gives a further command to actually go to normal 2Dmode. Thereto the processing means may be arranged for, while thegenerating means generate the pseudo 2D display signal, detecting thatrendering the 3D video data has ended, and, in response to thedetection, setting the generating means to generate the 2D displaysignal.

FIG. 4 shows controlling 3D playback when in the pseudo 2D mode. Thesequence of steps is performed when the user request to switch playbackmode from 2D to 3D, while the system is in pseudo 2D mode. Initially atstep 401 “Pseudo 2D” the system is generating the pseudo 2D displaysignal. At step 402 “Init 3D” the user may request the display mode togo to 3D. In step 403 “Detect 3D” the requested 3D display mode isregistered, e.g. in a status register. Subsequently the normal 3Ddisplay signal is generated at step “3D Playback” 404 by activating 3Dplayback in 3D mode so that Switch S1-1 . . . S1-3 toggle between L andR.

FIGS. 3 and 4 illustrate how the transition between 3D and 2D and backmay be performed when, during playback of a 3D (stereoscopic) movietitle, the user decides to change playback to 2D mode. The player setsthe player register that holds the current output mode to 3D. It thenchecks whether playback is currently active, if so the output mode ismaintained but playback of the auxiliary or dependent view is replacedby repeating the main view. This is achieved by keeping switch S1-1through to S1-3 in the “L” position (top position of switches S1-1 toS1-3 in FIG. 1-1). At the end of playback of the current title and atthe start of a new title the player device may check the status of theoutput player setting register and initiate playback in 2D if the userselects a title.

To achieve a smooth transition the playback device should maintain thesignaling on the interface the same. The interface typically used inBlu-ray Disc players is HDMI. Transmission and signaling of stereoscopiccontent over HDMI is defined in the specification. There are severalstereoscopic video formats that can be transmitted over HMDI, here wewill only explain how one commonly used format is transmitted namelyframe alternative stereoscopic video, similar principles apply totransmission and signaling of other stereoscopic video formats (linealternative, side-by-side, checkerboard etc). In the examples of FIG. 5a display signal according to the HDMI standard is shown. However, anyvideo signal that has a format to control a 3D video display may besimilarly adapted to implement the pseudo 2D mode.

FIG. 5A shows a 3D display signal. The timing and blanking periods usedwhen transmitting frame alternative stereoscopic video according toHDMI. Signaling to indicate where the left frame ends and the rightframe begins is done by inserting a vertical blanking period. A typicaltiming for this format would be 1920×1080 at 24 fps and with a Vfreq of24 Hz and blanking periods of Hblank 830, Vblank 45 with the pixel clockrunning at 148.500 MHz.

FIG. 5B shows a display signal for normal 2D playback. For example thesignal may carry 1920×1080 video at 24 fps with Vfreq of 24 Hz andblanking periods of Hblank 830, Vblank 45 with a pixel clock of 74.250MHz. Although the signaling of both these formats are similar the pixelclock runs twice as fast and there is an additional vertical blankingperiod in the stereoscopic format. Changes to the pixel clock willtypically require re-configuration of the interface and cause frameloss. Therefore the pseudo 2D display signal is proposed for 2D/3D modechanges during playback.

FIG. 5C shows a display signal for pseudo 2D playback. In the signal thepixel frequency is maintained at the level of the 3D signal shown inFIG. 5A, but that the Right frame is replaced by repeating the Leftframe as is shown. In particular the Vertical Frequency signal marks thedifference with the normal 2D signal of FIG. 5B.

The Blu-ray Disc standard uses a playlist structure to define all thesignaling required for a player to playback a 2D or 3D title. A playlistis a sequence of playitems, a playitem is a list of segments of a streamthat together make up the presentation (Video, Audio streams, subtitlesand other graphics). Inside every playitem there is a table that listsall the elementary streams that are decoded and presented duringplayback of the playitem, this table is referred to as the STreamNumber(STN)-table; see FIGS. 7A and 7B.

In an embodiment when transitioning between 3D and 2D playback an offsetis applied to the 2D image and also to the graphics. 2D image data isused to generate 3D data as illustrated in FIG. 6. The generating unitas discussed above are arranged for, when transitioning between the 3Dmode and the pseudo 2D mode, to apply a 3D offset to the 2D video datafor changing the amount of 3D information.

The offset may be stored on the disc in a table and may be used when theplayback device does not support full 3D stereoscopic playback.Alternatively the offset may be a predefined value set in the player, orselected by the user, etc.

When transitioning between 3D and 2D and back the offset may begradually applied to the main 2D image when switching from 2D to 3D andgradually reduced when transitioning between 3D and 2D. Thereto thegenerating means are arranged for applying the 3D offset gradually forgradually changing the amount of 3D information.

FIG. 6A shows applying a 3D offset. An example of 2D image data 601 iscombined with graphical 2D data 602, which is to be positioned in depthdirection in front of the background image 601. The combined image isused as a left view 607. An offset 606 is applied to graphical 2D data603 as a disparity shift to generate a right view 608. The user willexperience a combined 3D view 609. Due to the shift a part 604 of thegraphics is cropped, while a further part remains blank or transparentbecause no information is available to fill the area.

For stereoscopic graphics created by applying an offset to a 2D imageproblems can occur when the offset is applied on the 2D image in onedirection. When the relevant part of the 2D image is located near theborder of the plane after applying an offset part of the image may fallbeyond the boundaries of the plane as is shown in FIG. 6A at element610, element 619 and 622 of 6B. The numeral 1 will partly disappear inthe final view 609.

FIG. 6B shows applying a dual 3D offset. The offset is divided by 2 andapplied to both the Left and the Right output plane (but in oppositedirections) of graphical 2D data 620 and 621. By applying half of theoffset 625 to generate both output planes, so on the 2D image in bothdirections, the cropping effect can be reduced as is shown in FIG. 6B.Thereto the generating means are arranged for applying the 3D offset byshifting 2D video in opposite directions to generate a left output planeand a right output plane.

FIG. 6C shows avoiding border cut-off while applying offset. The Figureshows a re-edited version of the graphics information. The left offsetversion 630 and the right offset version 631 both do not containelements in the cropped parts 632, 633. Hence the final view is improvedby during authoring ensuring that the image+the applied offset remaininside the boundaries of both left and right planes.

In a further embodiment non-linear stretching and scaling is applied toboth the left and right view when using an offset applied to a 2D imageto create a stereoscopic perception. When applying an offset andshifting the image to the left and/or right parts of the (video and/orgraphics) image background is de-occluded. In case that there is nobackground information available to fill in those de-occluded areas theoutput image is cropped. To avoid the user being disturbed by thissudden cropping of the image the image is scaled non-linearly to fill inthe missing de-occluded areas. Thereto the generating means are arrangedfor non linear stretching of the 2D video during said shifting forcovering parts of the 3D signal that would remain blank on the displaydue to said shifting.

FIGS. 7A and 7B show a stream number table, which defines the variousdata streams in the 3D video signal, called STN_table_3D. The tableshows an example of an STN_table_3D for one playitem. Additional entries(as discussed below) are included to a regular 2D STN_table. Anauxiliary stream entry may reference a dependent stream as is the casewith stereoscopic video or may contain a depth map stream or both.Typically the main entry will contain the independent video forstereoscopic video, e.g. encoded according to MPEG-4 MVC, while thesub-path of the auxiliary stream can be used to refer to a depth- ordisparity map that is selected in combination with or instead of thedependent video stream.

For playback of a playitem that contains 3D content such as a MPEG MVCstream, that consists of a main and a dependent elementary stream, theSTN_table is extended to support signaling to identify not only the mainvideo stream (as is the case for normal) 2D playback, but also thedependent stream for the 3D data. Two options are available forincluding this information. A new playlist type may be defined or theadditional signaling is added as extension data to the playlist which anexisting player will ignore. In both cases a new entry to the STN_tableis added that contains an entry for every (stereoscopic) 3D streambeyond the base view viz. the dependent or secondary view streams. The3D enhanced STN_table is referred to as the STN_table_3D and typicallyfor compatibility reasons would be added as extension data to a playlistwhereby the STN_table_stereoscopic has a loop of playitems and perplayitem contains the stream entries for the main and auxiliary streams.

The following fields are to be noted in the STN table for defining theSTN_table_3D Semantics:

length: This 16 bit field indicates the number of bytes of theSTN_table( ) immediately following this length field and up to the endof the STN_table( ).

keep_3D_mode_during_playback

This field indicates the behavior of the player when transitioning from3D to 2D mode during playback of a movie title. If set to 0b then theplayer switches modes. If set to 1b the player will maintain the mode in3D but the player will maintain the L, R plane switches S1-1 . . . S1-3in the “L” position such that the presentation of the video and/orgraphics content goes to 2D by generating the pseudo 2D signal. Thissignal may be maintained until playback of the current running titlestops or until the user changes playback mode back to 3D.stream_entry( ) This section defines the stream_entry( ) of theSTN_table( ); see FIG. 8 stream_entry_auxilliary_view( ) This entrydefines the additional video data stream that constitutes 3Dinformation, such as a dependently coded Right view or depth map. Syntaxand semantics are the same as for the stream_entry of the main view.stream_attributes( ) This field defines the stream_attributes( ) of theSTN_table( ) see FIG. 10.

In an embodiment, instead of one STN_table_3D for a whole playlist, anSTN-table_3D may be added to each playitem. Furthermore, a new playlistspecifically for 3D playback may be defined, instead of an extension toa 2D playlist.

To minimize transition delays and artifacts during transitions between3D back to 2D mode a new entry, called switching indicator, can be addedthat allows the content author to indicate the desired behavior during atransition between 3D to 2D and vice versa. The switching indicator isindicative of a 2D mode to be selected. The options for this selectionare: (a) to switch player modes or (b) to indicate to continue playbackin 3D mode but with zero disparity (pseudo 2D mode).

For accommodating the switching indicator in the video device of FIG. 1,the receiving means are arranged for retrieving, from the 3D videosignal, the switching indicator. The processing unit 53 is arranged for,when detecting said request to display 2D video data, setting thegenerating means to generate the display signal in dependence of theswitching indicator to either the 2D mode or the pseudo 2D mode.

In an embodiment the field keep_3D_mode_during_playback 71, 72, 73 is anexample of the switching indicator that indicates the pseudo 2Dswitching mode is to be selected, or normal 2D mode. In the example theindicator 71 is provided for the main video data, a further indicator 72is provided for the presentation graphics data and a further indicator73 is provided for the interactive graphics data. Note that in otherembodiments this field may be omitted, may be just one indicator for allstreams, or may be extended to indicate further conditions of 2D/3D modeswitching.

A method of providing the 3D video signal comprises generating the 3Dvideo signal comprising 3D video data, and including the switchingindicator in the 3D video signal. The 3D video signal thus generated maybe transferred via a network, broadcasted, stored on a record carrier,etc. The method may further include the step of manufacturing a recordcarrier, the record carrier being provided with a track of marksrepresenting the 3D video signal.

FIG. 8 shows a stream entry. The stream entry defines the parameters ofthe respective stream. In particular the following fields are to benoted in the stream entry table for defining the syntax:

length: This 8 bit field indicates the number of bytes of thestream_entry( ) immediately following this length field and up to theend of the stream_entry( ).

type: This 8-bit field indicates the type of database for identifying anelementary stream referred to by a stream number for the stream_entry( )see FIG. 9.

ref_to_stream_PID_of_mainClip: This 16-bit field indicates a value fromthe stream_PID[0][stream_index] entries defined in the ProgramInfo( ) ofthe Clip referrd to by theClip_Information_file_name[0]/Clip_Information_file_name[angle_id] ofthe PlayItem( ).ref_to_SubPath_id: This 8-bit field indicates a value from SubPath_identries defined in the PlayList( ).ref_to_subClip_entry_id: This 8-bit field indicates a value from thesubClip_entry_id entries defined in a SubPlayItem of the SubPath referrdto by the ref_to_SubPath_id.ref_to_stream_PID_of_subClip: This 16-bit field indicates a value fromthe stream_PID[0][stream_index] entries defined in the ProgramInfo( ) ofthe Clip referrd to by the Clip_Information_file_name referrd to by theref_to_subClip_entry_id.

FIG. 9 shows a table for defining the type in the stream entry. Thevalue of Type identifies the structure of the respective stream in the3D video signal, as indicated in the table.

FIG. 10 shows the syntax of stream attributes. The stream attributes arepart of the STN table as shown in FIGS. 7A and 7B. In particular thefollowing fields are to be noted in the stream attribute syntax:

length: This 8 bit field indicates the number of bytes of thestream_attributes( ) immediately following this length field and up tothe end of the stream_attributes( ).

stream_coding_type: This 8-bit field indicates the coding type of theelementary stream associated with a stream number for thestream_attributes( ), and shall be set to a predefined value, e.g. 0x20to indicate a MVC coded dependent stream or 0x21 to indicate a depth ordisparity map.

It will be appreciated that the above description for clarity hasdescribed embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits or processors may be used without detracting from the invention.For example, functionality illustrated to be performed by separateunits, processors or controllers may be performed by the same processoror controllers. Hence, references to specific functional units are onlyto be seen as references to suitable means for providing the describedfunctionality rather than indicative of a strict logical or physicalstructure or organization.

The invention can be implemented in any suitable form includinghardware, software, firmware or any combination of these. The inventionmay optionally be implemented at least partly as computer softwarerunning on one or more data processors and/or digital signal processors.The elements and components of an embodiment of the invention may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, theinvention may be implemented in a single unit or may be physically andfunctionally distributed between different units and processors.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present invention is limitedonly by the accompanying claims. Additionally, although a feature mayappear to be described in connection with particular embodiments, oneskilled in the art would recognize that various features of thedescribed embodiments may be combined in accordance with the invention.In the claims, the term comprising does not exclude the presence ofother elements or steps.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by e.g. a single unit orprocessor. Additionally, although individual features may be included indifferent claims, these may possibly be advantageously combined, and theinclusion in different claims does not imply that a combination offeatures is not feasible and/or advantageous. Also the inclusion of afeature in one category of claims does not imply a limitation to thiscategory but rather indicates that the feature is equally applicable toother claim categories as appropriate. Furthermore, the order offeatures in the claims do not imply any specific order in which thefeatures must be worked and in particular the order of individual stepsin a method claim does not imply that the steps must be performed inthis order. Rather, the steps may be performed in any suitable order. Inaddition, singular references do not exclude a plurality. Thusreferences to “a”, “an”, “first”, “second” etc do not preclude aplurality. Reference signs in the claims are provided merely as aclarifying example shall not be construed as limiting the scope of theclaims in any way.

The invention claimed is:
 1. A device for processing a video signalcomprising: an input circuit, the input circuit configured to receivethe video signal and a video data, wherein the video data comprisesthree-dimensional video data and two-dimensional video data, wherein thethree-dimensional video data provides a single sequence ofthree-dimensional images, wherein the two-dimensional video dataprovides a single sequence of two-dimensional images; a generatingcircuit, the generating circuit configured to generate an output signalfor transferring the video data via a high-speed digital interface,wherein the output signal transfers the video data to athree-dimensional display, wherein the generating circuit comprisesgenerating a three-dimensional display signal for displaying thethree-dimensional video data, wherein the three-dimensional signalcomprising a left eye view and a right eye view, wherein the generatingcircuit generates a two-dimensional display signal formatted as athree-dimensional video display signal for displaying onlytwo-dimensional video data on the three-dimensional display, wherein thethree-dimensional display is operative in a two-dimensional mode,wherein the generating circuit generates each of the two-dimensionalimages in both the left eye view and the right eye view by includingtwo-dimensional video data in the output signal in the format of athree-dimensional signal to enable the two-dimensional video data to bedisplayed on the three dimensional display when the three-dimensionaldisplay is operative in the three-dimensional mode; and a processorcircuit, wherein the processor circuit detects a transition signal,wherein the transition signal indicates a transition from displaying thethree-dimensional display signal in the three-dimensional mode todisplay two-dimensional video data on the three-dimensional display,wherein, in response to the transition signal, the processor circuitselects the generating circuit to generate each of the two-dimensionalimages in both the left eye view and the right eye view from the videodata to maintain the three-dimensional mode of the three-dimensionaldisplay, thereby enabling a continuous viewing of the sequence ofthree-dimensional images followed by the sequence of two-dimensionalimages, without visual anomalies.
 2. The device of claim 1, wherein thegenerating circuit, generates the two-dimensional video data by derivingimage data without three-dimensional information from thethree-dimensional video data while generating each of thetwo-dimensional images in both the left eye view and the right eye view.3. The device of claim 2, wherein the generating circuit, changes theamount of three-dimensional information displayed by applying athree-dimensional offset to the two-dimensional video data whentransitioning between the three-dimensional mode and generating each ofthe two-dimensional images in both the left eye view and the right eyeview.
 4. The device of claim 1, wherein the processor circuit combinesgraphical data and video data by positioning the graphical data in depthdirection in front of the two-dimensional video data by applying anoffset to the graphical data to generate each of the two-dimensionalimages in both the left eye view and the right eye view.
 5. The deviceof claim 3, wherein the generating circuit gradually changes the amountof three-dimensional information by applying the three-dimensionaloffset gradually.
 6. The device of claim 3, wherein the generatingcircuit applies the three-dimensional offset by shifting two-dimensionalvideo or graphical data in opposite directions to generate a left outputplane and a right output plane.
 7. The device of claim 5, wherein thegenerating circuit covers one or more blank parts of thethree-dimensional display signal by non-linearly stretching thetwo-dimensional video during the application of the three-dimensionaloffset, wherein the one or more blank parts are due to the applicationof the three-dimensional offset.
 8. The device of claim 1, wherein theprocessor circuit detects that rendering the three-dimensional videodata has ended, wherein the processor circuit sets the generatingcircuit to generate the two-dimensional display signal in response tothe detection, while the generating circuit generates each of thetwo-dimensional images in both the left eye view and the right eye view.9. The device of claim 1, wherein the input circuit retrieves, from thethree-dimensional video signal, a switching indicator, wherein theswitching indicator is indicative of a two-dimensional mode to beselected, wherein the processor circuit, sets the generating circuit togenerate the output signal in dependence on the switching indicator toeither the two-dimensional display signal or each of the two-dimensionalimages in both the left eye view and the right eye view when detectingthe transition signal to display two-dimensional video data.
 10. Thedevice of claim 1, wherein the input circuit includes a record carrierreader for reading a record carrier for receiving the three-dimensionalvideo signal.
 11. The device of claim 1, further comprising thethree-dimensional display.
 12. A method of processing a video signal,the method comprising receiving the video signal and a video data,wherein the video data comprises three-dimensional video data andtwo-dimensional video data, wherein the two-dimensional video data doesnot provide sufficient information to enable construction ofstereoscopic images, wherein the three-dimensional video data provides asingle sequence of three-dimensional images, wherein the two-dimensionalvideo data provides a single sequence of two-dimensional images;generating an output signal for transferring the video data via ahigh-speed digital interface to a three-dimensional display, wherein thegenerating comprises generating a three-dimensional display signal fordisplaying the three-dimensional video data, wherein thethree-dimensional signal comprises a left eye view and a right eye view,on the three-dimensional display, wherein the three-dimensional displayis operative in a three-dimensional mode; generating a two-dimensionaldisplay signal formatted as a three-dimensional video display signal fordisplaying only two-dimensional video data on the three-dimensionaldisplay, wherein the three-dimensional display is operative in atwo-dimensional mode; generating each of the two-dimensional images inboth the left eye view and the right eye view by includingtwo-dimensional video data in the output signal in the format of athree-dimensional signal to enable the two-dimensional video data to bedisplayed on the three-dimensional display when the three-dimensionaldisplay is operative in the three-dimensional mode; detecting atransition signal, wherein the transition signal indicates a transitiondisplaying the three-dimensional display signal in the three-dimensionalmode to display two-dimensional video data on the three-dimensionaldisplay; and, in response to the transition signal, selecting thegenerating to generate each of the two-dimensional images in both theleft eye view and the right eye view from the video data to maintain thethree-dimensional mode of the three-dimensional display, therebyenabling a continuous viewing of the sequence of three-dimensionalimages followed by the sequence of two-dimensional images, withoutvisual anomalies.
 13. The method as claimed in claim 12, wherein thegenerating includes a switching indicator in the three-dimensional videosignal, wherein the switching indicator indicates a two-dimensional modeto be selected, wherein detecting the transition signal to displaytwo-dimensional video data generates the output signal in dependence onthe switching indicator to either the two-dimensional mode or each ofthe two-dimensional images in both the left eye view and the right eyeview.
 14. The method as claimed in claim 12, further comprisingmanufacturing a record carrier, wherein the record carrier is providedwith a track of marks representing the three-dimensional video signal.15. A computer-readable, non-transitory medium having stored thereininstructions for causing a processing circuit to execute a method forprocessing a video signal, the medium comprising code for: receiving thevideo signal and a video data, wherein the video data comprisesthree-dimensional video data and two-dimensional video data, wherein thetwo-dimensional video data does not provide sufficient information toenable construction of stereoscopic images, wherein thethree-dimensional video data provides a single sequence ofthree-dimensional images, wherein the two-dimensional video dataprovides a single sequence of two-dimensional images; generating anoutput signal for transferring the video data via a high-speed digitalinterface to a three-dimensional display, wherein the generatingcomprises generating a three-dimensional display signal for displayingthe three-dimensional video data, the three-dimensional signalcomprising a left eye view and a right eye view, on thethree-dimensional display, wherein the three-dimensional display isoperative in a three-dimensional mode; generating a two-dimensionaldisplay signal formatted as a three-dimensional video display signal fordisplaying only two-dimensional video data on the three-dimensionaldisplay, wherein the three-dimensional display is operative in atwo-dimensional mode; generating each of the two-dimensional images inboth the left eye view and the right eye view by includingtwo-dimensional video data in the output signal in the format of athree-dimensional signal to enable the two-dimensional video data to bedisplayed on the three-dimensional display when the three-dimensionaldisplay is operative in the three-dimensional mode; detecting atransition signal, wherein the transition signal indicates a transitionfrom displaying the three-dimensional display signal in thethree-dimensional mode to display two-dimensional video data on thethree-dimensional display; and, in response to the transition signal,selecting the generating to generate each of the two-dimensional imagesin both the left eye view and the right eye view from the video data tomaintain the three-dimensional mode of the three-dimensional display,thereby enabling a continuous viewing of the sequence ofthree-dimensional images followed by the sequence of two-dimensionalimages, without visual anomalies.
 16. The medium of claim 15, comprisingcode for generating the two-dimensional video data by deriving imagedata without three-dimensional information from the three-dimensionalvideo data while generating each of the two-dimensional images in boththe left eye view and the right eye view.
 17. The medium of claim 15,comprising code for applying a three-dimensional offset to thetwo-dimensional video data for changing the amount of three-dimensionalinformation displayed, when transitioning between the three-dimensionalmode and displaying each of the two-dimensional images in both the lefteye view and the right eye view.
 18. The medium of claim 17, comprisingcode for gradually changing the amount of three-dimensional informationby applying the three-dimensional offset gradually.
 19. The medium ofclaim 17, comprising code which cover one or more blank parts of thethree-dimensional display signal by for non-linearly stretching thetwo-dimensional video during the application of the three-dimensionaloffset, wherein the one or more blank parts are due to thethree-dimensional offset.
 20. The medium of claim 15, comprising codefor detecting that rendering the three-dimensional video data has ended,and, in response to the detection, setting the generating circuit togenerate the two-dimensional display signal while generating each of thetwo-dimensional images in both the left eye view and the right eye view.